B.C. study among the first to compare the effects of different strains of cannabis on PTSD

By Amanda SiebertMay 31st, 2017

The UBC study led by Zach Walsh is one of the first to compare how two different strains of marijuana might affect patients with PTSD.

B.C. scientists are conducting a study that is one of the first to compare the way different strains of marijuana might affect patients suffering from posttraumatic stress disorder (PTSD).

Leading the team of researchers is Zach Walsh, a clinical psychologist and an associate professor at the University of B.C.’s Okanagan campus.

For Walsh, the need for research that backs up claims made by veterans’ groups, patients, and advocates has reached a critical point.

“It’s the patients leading the way on this, and they’re using cannabis, so it’s our job as health scientists to figure out if it’s working,” Walsh tells the Georgia Straight by phone.

He says the need for empirical data is one that can’t be ignored in light of the disorder’s prevalence in Canada: in 2016, the British Journal of Psychiatry reported that among a group of 16 countries—including the United States, Australia, South Africa, Iraq, and Israel—Canada had the highest lifetime PTSD–prevalence rate, at 9.2 percent.

Typically, Walsh says, PTSD patients are prescribed a cocktail of pharmaceuticals that can include antidepressants, sleeping pills, and even antipsychotics.

Although some drugs can be helpful in mitigating symptoms, there are no drugs specifically formulated for patients with the disorder. (Health Canada has approved one antidepressant drug, Paroxetine, for PTSD, but studies have shown that it can lead to increased thoughts of suicide among patients.)

“The nice thing about cannabis, in comparison, is that the side effects line up much more favourably,” Walsh says.

“Some might have a tough time with the cognitive effects caused by the high, but for most people, that’s a much more tolerable side effect compared to those of other treatment options.”

Walsh hopes that through the trial, patients will be able to reduce or eliminate symptoms like irritability, anxiety, insomnia, nightmares, and traumatic flashbacks.

Zach Walsh is a clinical psychologist and an associate professor at the University of B.C.’s Okanagan campus.

The trial won’t focus specifically on armed-forces veterans but on patients with PTSD of any cause. They’ll include assault victims, first responders, and victims of motor-vehicle accidents, among others.

Every participant in the triple-blind study received a vaporizer and is using two of three treatments for a period of three weeks each. The first is a placebo without active ingredients. The second, a tetrahydrocannabinol (THC)-dominant strain, contains 12 percent of the well-known compound. The third strain contains 12 percent each of THC and cannabidiol (CBD). All cannabis is provided by Tilray, a Nanaimo-based licensed producer that has partnered with UBC for the trial, which is the largest of its kind to take place in Canada during the last 40 years.

Walsh says that although the cannabis industry seems obsessed with comparing the efficacy of different compounds and strains, few studies, if any, have taken that obsession to heart.

Dr. Ian Mitchell, an emergency physician in Kamloops and the clinician working on the trial, is responsible for the medical safety of the patients involved.

Mitchell says it’s too early to tell what the results will be, but anecdotal evidence from patients with PTSD in his own clinical practice has shown cannabis to be helpful. He has been referring patients to Canada’s ACMPR (Access to Cannabis for Medical Purposes Regulations) program for the past three years.

“I have a lot of patients who are enthusiastic to be using it. I’m seeing a lot of RCMP veterans in my practice with PTSD who are able to sleep again—but you get a double effect, because it also helps with pain,” Mitchell tells the Straight by phone.

He adds that when patients come to him, they have often tried five or six different medications. He says cannabis not only can help with their PTSD symptoms but has also been effective in mitigating symptoms of withdrawal from those other drugs.

“We’ve got drugs that can cause [side effects such as] sudden death, obesity, hypertension, and it can be very damaging for people,” he says.

“So many people I see have not gained benefit from them—and many of them have very unpleasant withdrawal symptoms, so we don’t encourage patients to go cold turkey.”

The popularity of cannabis among PTSD patients has even prompted the federal government to conduct its own study for Canadian Armed Forces veterans.

As for the study Walsh and Mitchell are working on, it is expected to conclude in spring 2018.